The subject of the present analysis is the condensation of the environmentally friendly refrigerants R134a and R404A in long, serpentine pipe coils, for L-c/d > 800-1000, where L-c is the total length of the coiled pipe, and d is its internal diameter. During condensation in a coiled-pipe condenser, heat exchange occurs in three regimes, i.e., the superheat removal regimes, the two-phase condensation regimes and the condensate subcooling regimes. The length L of the two-phase area significantly affects the values of the average heat transfer coefficient alpha and the flow resistance (Delta p/L) in this area. On the basis of experimental investigations of the condensation process in a long, water-cooled serpentine coil with five pipe coils of differing dimensions, it was established that the condensation mechanism in a long coil pipe differs substantially from that in a horizontal pipe. New experimental correlations were developed to calculate the average heat transfer coefficient and flow resistance in the two-phase area. In these correlations, the dimensions of the two-phase area are characterized by the geometric index L/d. The correlations developed in this study may be useful in the design of water-cooled serpentine-coil condensers. (C) 2013 Elsevier Ltd. All rights reserved.